Looks like owners of non turbo 300d's have a new radiator available again.....
I have a 1981 with a leaky radiator and up until now, they have been discontinued. Looks like Summitracing has the lowest price but when I put in my cart it said it would be special ordered and shipped on 8/1/2014

Spectra PremiumŪ CU672 - Mercedes S Class 1980 Radiator

Spectra Premium/Radiator (B672) | AutoZone.com

http://www.summitracing.com/parts/sgt-cu672